Clicking okular menu bar, then hovering over it messes the menu up

I’m not using kde, but I rather like okular, especially to annotate pdfs. So I hope it’s ok to ask this question here to help get it working again.

When I upgraded to debian bookworm, my okular menu sort of broke, as you can see from the attached screen shot. It seems like it might be a profile UI problem, but I can’t be sure. I can’t tell if this is a bug or something I’m doing wrong.

For example, notice how “To” in the menu gets wiped out from “Tools”

I’ve tried both the standard bookworm package version 22.12.3 and the flatpak 23.08.4 version. Their menus are both broken in the same way. Update: I also installed on Windows 11 and it seems to work fine there.

If I run 22.12.3 from the terminal I don’t get any error messages.
When I run the flatpak I get some errors:

$ flatpak run org.kde.okular
Gtk-Message: 12:05:09.749: Failed to load module "xapp-gtk3-module"
Qt: Session management error: Could not open network socket
QWidget::setMinimumSize: (okular_sidebar/Sidebar) Negative sizes (0,-1) are not possible

Note, I have the package libxapp-gtk3-module installed and still get this error. But because I don’t get any errors when I run from the terminal, I’m not sure this has anything to do with this menu problem.

Also I’ve already tried clearing out all okular named config files in .confg and .local.

Debian bookworm is running X11, not wayland.

Any ideas on how to fix this, or should I perhaps be submitting a bug report? It seems like there must be something I’ve got wrong when I run this.

(I already posted this at Redit, but their bot suggested I post it here.)